Peridomestic and Neighborhood-Level Deciduous Land Cover Associated with Lyme Disease Risk: Results from a Case-Control Study in the United States.

INTRODUCTION

Lyme disease (LD), the most common vector-borne disease in the United States, is caused by the transmission of bacteria via the bite of infected Ixodes ticks including Ixodes scapularis. Deciduous forests are a highly suitable habitat for I. scapularis survival and development. This case-control study investigated how LD risk was impacted by residential proximity to deciduous forest land cover.

MATERIALS AND

METHODS

Participants were selected from the Optum Research Database and mailed a one-time survey regarding LD history, outdoor activities, residential characteristics, and demographics. Cases were identified through the combination of LD diagnosis codes and antibiotic treatment in claims data during January 2020-January 2022; controls were matched based on residential county and census block group housing density. The National Land Cover Database was used to identify the presence and proportion of deciduous land cover within a 50 m and 500 m radius of participants' residential addresses.

RESULTS

LD was associated with deciduous land cover when present at both a 50 and 500 m radius (odds ratio [OR] = 1.80, 95% confidence interval [CI]: 1.33-2.44) and when present at the 500 m radius only (OR = 1.40, 95% CI: 1.04-1.88). Odds of LD also significantly increased with increasing deciduous cover. Independent of residential proximity to deciduous land cover, spending time in yards or hiking/walking/running in wooded/grassy areas was associated with LD. Stratified stepwise models showed that for individuals with deciduous land cover within both 50 and 500 m, risk was uniformly elevated regardless of activity, whereas outdoor activities were significant predictors in individuals with deciduous land cover within the 500 m radius only or within neither radius.

CONCLUSION

This study identified the presence of deciduous land cover as a key indicator associated with increased LD risk, though outdoor activities conferred increased risk independent of residential land cover. Furthermore, individual behaviors were found to modulate LD risk differently across residential contexts.